The difference is in the degree of change applied to the object.
Enhancing leaves the main structure and functionality the same, most features intact, and generally speaking improves the object by applying small modifications.
Revamping often changes the basis, some fundamentals, some key features. Structure can undergo some changes, but the functionality generally is kept as is although we can see re-prioritizing of some elements.
Overhauling involves disassembling into constituent parts, examining each of them carefully for flaws, replacing with equivalent new parts (subsystems), in order to bring the system's performance closer to the original specification/idea.
Those words are not interchangeable. You could overhaul an engine of an aircraft to bring the engine back to its "factory new" performance. You could enhance an engine of an aircraft by replacing some heavier parts with lighter ones, for instance. You wouldn't revamp an engine. The latter most often used to describe a process for making fixes in a social/business system, like government, company management, etc. You could, however, revamp a design of an engine, which often includes technological part (manufacturing).
Understandable = behaviour or reactions which seem normal and reasonable, as in
His unwillingness to go through all that again is quite understandable.
It is understandable that parents are angry, and looking for someone to
blame.
Replace it with comprehensible and the simple sentences take on an odd, stilted air.
On the other hand, comprehensible rather implies intelligibility than normality (the more so, since the word comprehensible is heavily used in scientific papers):
The epistemological project feels like the pursuit of a perfectly
comprehensible intellectual goal. The explanation of the science at
work was clear, concise and comprehensible.
Replace it with understandable and the latter begins to seem a bit out of discourse.
Best Answer
On tangerines and mandarins, clementines and satsumas
When discussing words used “in common practice” by a speech community comprising on the order of a billion speakers (~40% L1 + ~60% L2) distributed across the entire planet, sweeping generalities of usage are next to impossible.
Technical usage by scientists recognizes all of these things as various species and cultivars under the Citrus genus, but when they do so they use taxonomic binomials bearing little to no relationship to the words commonly used by these fruit. And even at the technical level, citrus taxonomy is confusing.
When used as a commonplace marketing term, words like tangerine and mandarin have no technical meaning, especially not one that is recognized across all corporations everywhere.
Wikipedia reports in their article on the tangerine:
In the United States, the “tangerine group” (non-oranges) have taken off in recent years, so people are finally starting to notice them. However, not everybody calls them the same thing. My nieces call the little ones cuties to mirror a brand name. That said, I don’t think they’ve ever tried a kumquat, which gives me a delightful idea for a Christmas stocking stuffer!